<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<script>
			function type(x) {
				if(x === null) {
					return 'null';
				}

				var t = typeof x;

				if(t !== 'object') {
					return t;
				}

				var c = toString.call(x).slice(8, -1).toLowerCase();
				if(c !== 'object') {
					return c;
				}

				if(x.constructor == Object) {
					return c;
				}

				return 'unknown';
			}

			function isObject(obj) {
				return type(obj) === 'object';
			}

			function isFunction(fn) {
				return type(fn) === 'function';
			}

			function isString(str) {
				return type(str) === 'string';
			}
		</script>
	</body>

</html>